The present invention relates generally to a card printing apparatus for printing images on card substrates such as driver's licenses, employee badges, student cards, and the like. More particularly, the invention relates to a card-flipping device located in the printer and used for turning the card over so that both sides of the card can be printed with an image.
There are various known card printing apparatus which use a thermal printing process for producing colored images on card products. In general, these printing devices use a conventional thermal dye transfer printing method, wherein a thermal printing head thermally-transfers dyes from a dye ribbon to a surface of the card. The thermal dye ribbon contains thermal dye panels of different colors, typically cyan (C), magenta (M), yellow (Y), which are arranged in a repeating pattern. The dye ribbon may contain a black thermal dye panel (K) in some instances. The printer can produce a full-colored image on the card's surface by combining the three primary colors. Generally, the card must make three separate passes under the print head (i.e., one pass for each color) in order to produce this full-colored image.
Many conventional thermal printers are built compactly and contain only one printing station for printing images onto one surface of the card at a time. In many instances, however, it is necessary to print images on both sides of the card. Also, it often is desirable to laminate a protective film over the printed images. Thus, card-flippers or card-inverters have been developed. The card is printed on one surface and then conveyed to a card-flipper located within the printer, which rotates the card 180 degrees, so that the opposing surface of the card faces upwardly and can be printed thereon.
More particularly, card-turning devices, which use a set of rollers for conveying the card to the card-turning device, are known in the art. For example, Fulmer, U.S. Pat. No. 6,279,901 discloses a card inverter that includes a plate for supporting the card and a set of rollers for moving the card through the inverter and clamping the card. A stepper motor is used for powering a drive housing which rotates the card support plate so that the card is flipped 180 degrees. Thus, the inverter rotates the card about a central axis that bisects the card so the card plane is maintained in the first position and inverted position.
Kobayashi, U.S. Pat. No. 5,771,058 discloses a card-turning device for use with a card printer. The card-turning device comprises a rotary body rotatable on its own axis, which is provided with roller units, and a turning means for rotating the rotary body about the axis, and a card feeding means for driving at least one of the roller units. The card printer sends the card having one printed side into the card-turning device united with the card printer along a card feed passage by driving the card feed means. The card, which is fed into the card-turning device, is retained in position between the paired feed rollers. Then, the rotary body is rotated 180 degrees to turn the card upside down.
Cuo et al., U.S. Pat. No. 6,318,914 discloses a card-reversing device for use in card printers to perform printing on both sides of a card such as a credit card or telephone card. The card-reversing device includes a rotary means capable of retaining and turning the card upside down, a transmission unit that includes feeding and idle rollers capable of feeding the card, a lock means capable of controlling the rotation of the rotary means, and a friction medium that provides a rotation torque transporting from the transmission unit for the rotation of the rotary means. The '914 patent discloses that the card-turning device is capable of turning over a card without causing damage when the turnover operation is abnormally stopped.
A different card-flipping mechanism is described in Nardone et al., U.S. Pat. No. 5,966,160 (“the '160 patent”). In the thermal printer described in the '160 patent, the card is placed on a rod-driven carriage or truck so that the dye-receptive surface of the card, which is to be printed thereon, faces upwards. The card-carrying carriage moves forward on guide rails and transports the card to a position under the thermal print head. Typically, the card is passed under the print head three successive times in order that each primary color dye can be applied to the card, and a full-colored image can be generated. After the dye-receptive surface of the card has been printed with the dye or dyes needed to produce the image, the carriage moves the card to a card-flipping station. As the carriage enters the flip station, a block assembly with card-retaining channels grasps the side edges of the card. A motor-driven cam assembly drives the block assembly upwards so that the card is lifted from the carriage. When the block assembly reaches a pre-determined vertical position, a stepper motor automatically rotates the card-retaining channels by 180 degrees so that the card is flipped-over. The block assembly is then lowered back to its initial starting position, and the card is returned to the carriage with its unprinted surface facing upwards. Then, the carriage is driven again through the thermal printing station to produce a printed image on the reverse surface of the card. In this manner, both the front and back sides of the card are printed with images.
One disadvantage with the card-flipping system described in the '160 patent is that it uses two motors. The cam system which moves the block assembly between the lower and upper positions includes a drive motor. In addition, a separate stepping motor causes the card-retaining channels to rotate and turn the card over. It would be desirable to have a card-flipping system that uses only a single motor means. One object of the present invention is to provide a card-flipping device that includes a motorized means for lifting the card from the carriage, and a non-motorized means for flipping the card over.
Secondly, in the printer of the '160 Patent, the card is held in the card-retaining channels by means of a spring biasing means. Particularly, the '160 Patent discloses a system, where the outer retaining channel is mounted on a bearing and includes a spring so that the channel is biased inwardly. The channel engages and retains the card by this inward biasing force. Although these card-retaining channels are generally effective for holding the card in place, it would be desirable to have improved card-retaining guides that could grip cards of varying thickness. One object of the present invention is to provide a card-flipping device having improved card-retaining guides.
These and other objects, features, and advantages of this invention are evident from the following description and attached figures.